The Surgery/Histology Core will provide the intellectual and physical environment in which Center Investigators, their trainees and support staff can learn and perform a variety of surgical and histological procedures. The Core will 1) maintain existing shared facilities for animal surgery, histological processing and electron microscopy and 2) provide technical expertise and training in surgical techniques (both acute and chronic) and histological techniques for tissue processing of both peripheral and central auditory structures at the light- and electron-microscopic levels. Some complex surgical techniques, such as preparation of the anesthetized cat for neurophysiological study, will be routinely offered as a technical service. Some histological processing will be performed as a technical service, but only when task complexity task and limited project scope makes it inefficient to train the relevant group. Facility maintenance will include 1) ordering of supplies, 2) preparation of stock solutions, 3) equipment repair, and 4) compliance with local and federal regulations. All research groups in the Center will benefit by the time saved in not duplicating these basic services. All investigators will also benefit in several ways from the repository of experience and expert advice the Core represents. First, significant time will be saved by offloading to Core personnel the task of training new students and new investigator-specific support staff. Second, Core expertise will enhance the research endeavors of all participants by 1) facilitating the incorporation of new techniques and 2) by allowing them to use a wide range of techniques, each on a phasic basis, without having to maintain all the requisite skills within their own group at any one point in time. Core personnel include three experienced individuals (only partial support is requested for each) with demonstrated expertise in all relevant areas, including animal surgery, immunohistochemistry and a wide range of embedding and staining techniques for light- and electron-microscopic evaluation of peripheral and central auditory structures.